Four-axis unmanned aerial vehicle



FIG. 1 is a top, front and right side perspective view of a four-axis unmanned aerial vehicle, showing my new design;

FIG. 2 is a top, rear and right side perspective view;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a rear elevational view thereof;

FIG. 5 is a right side elevational view thereof;

FIG. 6 is a left side elevational view thereof;

FIG. 7 is a top plan view thereof;

FIG. 8 is a bottom plan view thereof; and,

FIG. 9 is a partial enlarged view of FIG. 1 .

The broken lines in FIGS. 1 and 9 illustrate the periphery of the enlarged views of a four-axis unmanned aerial vehicle and form no part of the claimed design. 

CLAIM The ornamental design for a four-axis unmanned aerial vehicle, substantially as shown and described. 